Treatment of water



tive costs.

ited States The present invention relates generally to the treatment of water and, more particularly, it relates to the inhibition and prevention of corrosition and scale in various systems in which water circulates.

Coolng waters are used in many industrial plants, such as oil refineries, chemical plants, and other types of industrial plants, and are used in various types of equipment such as in heat exchangers, condensers, cooling towers, and associated distribution equipment. If available water supplies are used, scale and corrosion problems are usually experienced in the plants and equipment.

Controlling corrosion of metallic parts insystems employing cooling waters results in greater reduction of maintenance and operating cost. The degree of metallic corrosion by, aqueous solutions is dependent on such factors as temperature, flow rate, dissolved solids and oxygen content of cooling waters. Since the cooling waters used are obtained from different sources and have varied composition depending upon the geology of the terrain, and are contaminated with various amounts of corrosive gases such as H 5, mercaptans and corrosive liquids such as organic acids, no single method or material could be used as a cure-all for this purpose.

As used herein, the term sweet water" means water which does not contain compounds of the class of sulfides and mercaptans, whereas the term sour water is used to describe water containing one or more of those substances.

In the past, the widely used materials to inhibit corrosion of ferrous and non-ferrous metals and alloys in contact with cooling waters not contaminated with H 8 and mercaptans have been chromates. Phosphates have been used in both sweet and sour water systems. Chromates, undoubtedly, provide a greater degree of protection to metal attack by corrosive industrial waters,

only when used at high concentrations and, therefore, treating cooling waters with chromates results in prohibi- At low concentrations, chromates are ineffective for localized corrosion attack on metals. Chromates, however, cannot be used economically in sour water systems due to continuous reduction of hexavalent chromium to trivalent chromium by reducing gases, such as H 8, mercaptans, and the like. Furthermore, the toxicity of chromates poses a very diflicult problem of handling and disposal of water, treated with this material.

The relatively low cost and non-toxic phosphates have been used for controlling corrosion by cooling waters with very limited success. However, at high concentrations, depending upon the temeprature, flow rate, pH and dissolved solid contents of cooling water employed systems, the polyphosphates revert to relatively less efi'ecrtive orthophosphates of limited solubility. Attempts have been made to enhance the corrosion inhibition power of phosphates by addition of small quantities of materials such as cyanates, cyanides, manganates, zinc, silicate, organic materials and the like which are reported to have a synergistic effect on the ability of phosphates to reduce metal loss. Although mixtures containing phosphates and the above-mentioned materials have shown a definite improvement over phosphates alone in reducing atcnt ice and equipment which will limit corrosion and scale formation in the plants and equipment so as to provide improved heat transfer and to provide longer life to the plants and equipment.

A still further object of the invention is the provision of an improved water treating composition for addition the general corrosion attack, little or no beneficial efto sour water.

These and other objects of the invention are provided by mixing with water a soluble phosphate, a substituted alkyl pyridine and a quaternary ammonium salt. An organic chelating agent may be employed as a substitute for a portion of the quaternary ammonium salt.

The water soluble phosphates may be any of the polyphosphates, comprising pyrophosphate, tripolyphosphate, and the glassy polyphosphates, such as hexametaphosphate. The soluble phosphates of the invention may also include various orthophosphates. The water soluble salts will usually be the ammonium, potassium and sodium salts of the foregoing phosphate compounds.

The quaternary ammonium salt will be selected from the group consisting of compounds having one of the following general formulas:

In the formulas R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom; R is a radical, containing not more than six carbon atoms, selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals; and R and R radicals from the group consisting of alicyclic and alkyl groups. X is an anion which will form a water soluble salt with the cation and, by way of example, includes chloride, bromide, P0 ion, nitrates, and organic anions like acetate and propionate.

For purposes of this application, Formula 1 is referred to as a substituted imidazoline type quaternary ammonium salt and Formula 2 is referred to as a straight chain alkyl or aryl or alicyclic substituted type quaternary ammonium salt or mixture thereof.

The substituted alkyl pyridines are generally insoluble in water but can be solubilized to some degree by the presence of a cosolvent which, in the composition of the invention, is the quaternary ammonium salt. The substituted alkyl pyridines of this invention have alkyl chains which have from 6 to 10 carbon atoms in the alkyl chain. The alkyl chains may be substituted in the alpha, beta or gamma positions, either singly or in any two or all positions. The substituted alkyl pyridines of the invention will boil at temperatures in excess of about F., i.e. they are high boiling compounds.

The water soluble organic chelating compounds which can be used in this invention include ethylene diamine tetraacetic acid, or the water soluble salts thereof, dimethyl glyoxime, alpha benzoin oxime, alpha py-ridylhydrazine, and ethanolamines. These compounds are used as a substitute for some of the quaternary ammonium salts but they cannot be used in too large amounts as they may have corrosive properties. This class of chelating compounds is generally known in the art and various other compounds having similar chelating properties are known.

The composition of the invention has been found effective in the pH range from about 5.0 to about 8.5, but best Each of the foregoing compositions gave good results when added to sour water having from 50 to 80 p.p.m. of sulfur ion (2 valences), from 80 to 200 p.p.m. of calcium, 4O p.p.m. magnesium, 120 p.p.m. alkalinity as calcium results are obtained in the pH range from about 6.5 to 5 carbonate, 10 to 300 p.p.m. sulfate, 6 p.p.m. oxygen, and about 7.5. 15 to 200 p.p.m. chloride.

e tre e water of e {nventloll 001111911565 from The foregoing compositions also gave good results when about 1 i p- (p p to about g-P- added to sweet water having so to 200 p.p.m. of calcium, of the composition of the invention. For most available 40 magnesium 120 alkalinity as calcium water supplies, the composition of the invention will be 10 carbonate 10 to m. lf t 6 p p m oxygen and used at levels of from 20 to 30 p.p.m. for sweet waters 5 to 200 chloride: I

2 5 82113 ei all pl-l i d g zg l gut l g z'g-fmm about 1 (')I'lf1e treated waters had pI-Is from about 6.0 to about to about 100 p.p.m., the substituted alkyl pyridines are fixe the test but were PH employed at levels of from about .01 p.p.m. to about 0 er tests 10 ppm, and the quaternary ammonium compounds are n malsing the composition which is added to water, the added at levels from .1 p.p.m. to about 60 p.p.m. The alkyl pyndlhe ahdhuaterhary aihmohhuh salts are mlxed relative amounts of these compounds are desirably in the and thlshhxhhe is blended h the Phosphates following proportions, expressed as ratio of phosphate to product Is a damp but hoh'eahmg powder when hlgher quaternary ammonium compounds to substituted alkyl amounts P quaternary ammonium sahs and Shhshthted pyridines; 72:15:13, 93:6:1, 7222612. When the com- F are Hpwever, the pounds are mixed in these proportions, there is minimum h lhvehhoh. can be made to be free howmg h the scale formation and corrosion of ferrous and nomfermus tion of certain well known fillers, such as sodium sulfate, metal materials. While some benefits can be obtained Soda. mhhtes h If eomposihoh of the with mixtures outside theseranges, best results are vention is to be dissolved in high concentration for purtained in the particular range. Most satisfactory results Poses. 0f feeding the hher shohld not cause the PH of the are obtained with a mixture of compounds comprising solution to exceed about 7 since the composition of the 81 percent phosphate, 16 Percent of a quaternary invention is not soluble at high concentrations and high monium compound and 3 percent of Substituted alkyl pH values. A high concentration is an amount of the riding composition in excessof 1 pound per gallon of solution.

An organic chelating agent may be added up to levels 3, m ifi g of the of about 5 ppm. ven ion 0 ion is no a toget er own ut it appears Panticular examples of the compounds of he invem that it provides a protective coating to the equipment in don are set forth below which it is used and limits formation of scale on the equipment. In any event, ferrous and non-ferrous metals Example I are protected for extended periods of time by the use of Pam the composition of the invention and are provided with an golditlm hexamc aphosphzge t;s-ti-t-zgd a --l-il-; 50 effective barrier against corrosive action by sweet water a mary ammonium s su n imi azo e and sour water. The coating which a pears to be ro- W1 30 40 vided is sufficiently thin so that there is no problenh of Ethylene diamine tetraacetic acid 10 blockage in pipes and equipment. Furthermore, the thin- Alkyl Py g Point 1 ness of the coating is such as to assure maximum heat Example H v truagsfer leflicidelilicy. In addition, the apparent coating is s cient a Sodium hexametanhosphate inuu-ru-T- 150 protectiony 'erent to the metal surfaces to give long Quaternary ammomum Salt (substml'ted mlldmlme The various features of the invention which are beg lzy g point 240 F liezgd to be new are set forth in the following claims.

' e c aim: 1 Example 111 lLb-iA vlvlaterhtreating composition comprising a water hate so u e p osp ate selected from the groupconsisting of dfi g gg mfifi salt (Substituted imidazoline 2O orthophosphate and polyphosphate, a water soluble quatertype) 3 nary ammonium salt selected from the group consisting Ethylene diamine tetmaceu-c acid 1 of compounds hnvms the g eral rm a Substituted alkyl pyridine (boiling point 180 F.) 1 65 (ET R;

Example. IV Sodium tripolyphospliaie Y is i Quaternary ammonium salt (straight chain alkyl sub- N- stituted type) 5 9 Ethylene diamme tetraacetic acid 1 1 Substituted alkyl pyridine (boiling point 240 F.).... .s havmg the genjml @mula Example V RCH2N(R1R3)+X Sodium hexametaphosphate 15 and mixtures thereof, wherein R is a fatty acid and R Quaternary ammonium salt (straight chain aryl sub is a radical selected from the group consisting of jalicyclic stituted type) 3 and alkyl groups in which an alicyclic carbon atom is at- Ethylene diamine tetraacetic acid 1 taohed to the quaternary nitrogen atom, R is a radical Substituted alkyl pyridine (boiling point M0 F.) .8 fhontaining not more than 6 carbon atoms selected from c group consisting of hydrocarbon radicals, hydroxy Example VI hydrocarbon radicals and amino hydrocarbon radicals, Sodium liexamefaplinsphafe I 15 R and R are radicals selected from the group consisting Quaternary ammomum salt (straight chain alicyclic of alicyclic andalkyl groups, and X is an anion which substituted type) 3 will form a water soluble salt with the cation, and an alkyl Ethylene diamine tetraacetic acid 1 pyridine having an alkyl chain of from 6 to 10 carbon Substituted alkyl pyridine (boiling point 240 F.) .8 atoms.

2. A water treating composition comprising a water soluble phosphate selected from the group consisting of orthophosphate and polyphosphate, a water soluble quaternary ammonium salt selected from the group consisting of compounds having the general formula I N---C Rl Rz compounds having the general formula RCH,N R,R, +X

and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, an alkyl pyridine having an alkyl chain of from 6 to 10 carbon atoms, and a water soluble organic chelating agent selected from the group consisting of ethylene diamine tetraacetic acid, water-soluble salts of ethylene diamine tetraacetic acid, dimethyl glyoxime, alpha benzoin oxime, alpha pyridylhydrazine, ethanolamine, and mixtures thereof.

3. A water treating composition comprising a water soluble polyphosphate, a water soluble quaternary ammonium salt selected from the group consisting of compounds having the general formula compounds having the general formula RCH N(R R +X- and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, and alkyl pyridine having an alkyl chain of from 6 to 10 carbon atoms.

4. A water treating composition comprising a water soluble orthophosphate, a water soluble quaternary ammonium salt selected from the group'consisting of compounds having the general formula N' Rl Ra R4 compounds having the general formula RCH N(R R- +X and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R, is a radical containing not more than 6 carbon atoms selected from 11 %N--- R-C Ri \R: 1k B compounds having the general formula RCH N R R,) +X- and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, and alkyl pyridine having an alkyl chain of from 6 to 10 carbon atoms.

6. A water treating composition comprising sodium tripolyphosphate, a water soluble quaternary ammonium salt selected from the group consisting of compounds having the general formula N...- 4 r 1i[ R| compounds having the general formula RCH N(R R +X" and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclicandalkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R, and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, and alkyl pyridine having an alkyl chain of from 6 to 10 carbon atoms.

7. A water treating composition comprising sodium tripolyphosphate, a water soluble imidazoline type quaternary ammonium compound having the general formula wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R radicals are selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation and alkyl pyridine having an alkyl chain of from about 6 to carbon atoms.

8. A water treating composition comprising sodium tripolyphosphate, a water soluble straight chain alkyl substituted type quaternary ammonium salt having the general formula wherein R is a fatty acid, R is a radical consisting of an alkyl group, R is a radical containing not more than 6 carbon atoms and selected from the group consisting of alkyl hydrocarbon radicals, hydroxy alkyl hydrocarbon radicals and amino alkyl hydrocarbon radicals, and X is an anion which will form a water soluble salt with the cation, alkyl pyridine having an alkyl chain of from about 6 to 10 carbon atoms, and ethylene diamine tetracetic acid.

9. A water treating composition comprising sodium tripolyphosphate, a water soluble straight chain aryl substituted type quaternary ammonium salt having the general formula wherein R is a fatty acid, R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R3 is a radical containing not more than 6 carbon atoms selected from the group consisting of aryl hydrocarbon radicals, hydroxy aryl hydrocarbon radicals and amino aryl hydrocarbon radicals, and X is an anion which will form a water soluble salt with the cation, alkyl pyridine having an alkyl chain of from about 6 to 10 carbon atoms, and ethylene diamine tetracetic acid.

10. A water treating composition comprising sodium tripolyphosphate, a water soluble straight chain alicyclic substituted type quaternary ammonium salt having the formula wherein R is a fatty acid, R is an alicyclic radical, R is a radical containing not more than 6 carbon atoms selected from the group consisting of alicyclic hydrocarbon radicals, hydroxy alicyclic hydrocarbon radicals and amino alicyclic hydrocarbon radicals and X is an anion which will form a water soluble salt with thecation, alkyl pyridine having an alkyl chain of from about 6 to 10 carbon atoms, and ethylene diamine' tetracetic acid.

11. A cooling water solution comprising water, water soluble phosphate selected from the group consisting of I alkyl pyridine having an alkyl chain from about 6 to 10 compounds having the general formula RIRQ) +X- and mixture thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, in an amount from'about .l p.p.m. to about 60 p.p.m. and an alkyl pyridine having an alkyl chain from about 6 to 10 carbon atoms in the amount of about .01 p.p.m. to about 10 p.p.m., the pHof the solution being between about 6.5 and about 7.5.

13. A water treatment composition comprising water soluble phosphate selected from the group consisting of orthophosphate and polyphosphate, a quaternary ammonium compound selected from the group consisting of compounds having the general formula compounds having the general formula orthophosphate and polyphosphate in an amount from about 1 to about 100 p.p.m., a water soluble quaternary ammonium compound selected from the group consisting of compounds having the general formula compounds having the general formula RCH N(R R )+X- and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radical containing not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals, R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, in an amount from about .1 p.p.m. to about p.p.m. and an and mixtures thereof, wherein R is a fatty acid and R is a radical selected from the group consisting of alicyclic and alkyl groups in which an alicyclic carbon atom is attached to the quaternary nitrogen atom, R is a radicalcontaining not more than 6 carbon atoms selected from the group consisting of hydrocarbon radicals, hydroxy hydrocarbon radicals and amino hydrocarbon radicals,

R and R are radicals selected from the group consisting of alicyclic and alkyl groups, and X is an anion which will form a water soluble salt with the cation, and alkyl pyridine having an alkyl chain of from 6 to 10 carbon atoms, the ratio of said compounds being in the range from 72:15: 13, 93:6:1, and 72:26:2.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES NACE, Technical Committee Reports-Publication 53-3, vol. 11, No. 4, April 1955, pp. 6567. 

8. A WATER TREATING COMPOSITION COMPRISING SODIUM TRIPOLYPHOSPHATE, A WATER SOLUBLE STRAIGHT CHAIN ALKYL SUBSTITUTED TYPE QUATERNARY AMMONIUM SALT HAVING THE GENERAL FORMULA 